Radar is often used to detect objects and measure their ranges and speeds. For example, a radar system transmitter may transmit a pulse or modulated continuous wave of electromagnetic radiation, e.g. radio waves or microwaves. A radar receiver of the system may receive a pulse that was reflected by the object. The time-of-flight between transmission of the pulse and receiving of the pulse may be converted to a distance of the object.
The transmitted electromagnetic radiation may be formed into a narrow beam, or a radar receiver may be directional. For example, the beam may be shaped by suitable reflecting or refracting optics, or by a phased array. A narrow beam or directional receiver may enable detected objects to be distinguished from one another.
A component of velocity of an object toward or away from a radar system may be measured by exploitation of the Doppler Effect. Thus, measured change in a frequency of a wave, or a measured change in timing of wave pulses, reflected from an object may be indicative of a relative velocity of the object.